ADAM is a cysteine-rich molecule consisting of a disintegrin domain and a metalloprotease-like domain, which has been receiving much attention since it is a functional protein that not only exhibits metalloproteinase activity but also has adhesive activity. Most of ADAMs have transmembrane domains and localized in the cell membrane, thereby playing an extremely important role in molecular regulation on the cell surface. So far, 30 or more ADAM family proteins have been identified. Since the extracellular portion of ADAMs is involved in cell adhesion, cell fusion, proteolysis and intracellular signaling, they are implicated in fertilization, neurogenesis, myoblast fusion and cleavage of cytokines. In particular, since ADAM family proteins are membrane-anchored proteins that have similar structure to snake venom disintegrin, they are involved in various biological processes involving cell-to-cell and cell-to-matrix interactions (for example, fertilization, muscle development, neurogenesis and the like). Thus far, intensive research has been made on the search of novel ADAM molecule, clarification of their functions and methods for regulating them with the intention of drug discovery.
For example, ADAM-1 and ADAM-2 are believed to be involved in fertilization between egg and sperm via egg integrin (see Non-Patent Publication 1). ADAM-10 is suggested to be involved in control of Notch signal and plays an important role in neurogenesis, in processing of membrane protein and further in degradation of extracellular matrix component (see Non-Patent Publication 2). Recently, one type of aggrecanase which had been considered to be a degradative enzyme of aggrecan, i.e., a cartilage extracellular matrix, was purified and cloned, and reported to be a molecule of the ADAM family (see Non-Patent Publication 3). Therefore, development of a therapeutic drug for arthritis or osteoarthritis can be expected by regulating the enzyme activity of ADAM-10. ADAM-13 is expressed in xenopus laevis during embryogenesis, and considered to play an important role in its morphogenesis (see Non-Patent Publication 4). At this point, mammal-derived ADAM-13 has not been reported. ADAM-17 is known as a tumor necrosis factor (TNF) convertase (a synthase of soluble TNF). ADAM-17 inhibitors have been studied enthusiastically as prophylactic and/or therapeutic drugs for disorders caused by abnormal increase of TNF (inflammation, fever, malfunction of the circulatory system, graft-versus-host reaction, autoimmune disorder or the like). Methods for screening ADAM-17 itself and an ADAM-17 inhibitor have already been disclosed (see Patent Publications 1 and 2).
ADAM-15 is a transmembrane glycoprotein with a molecular weight of about 90 KDa that belongs to the ADAM family proteins. ADAM-15 has been found to have a function as an adhesion molecule involved in cell-to-cell adhesion via its disintegrin domain (see Non-Patent Publication 5). Among 20 or more ADAM family proteins, only human ADAM-15 has a RGD tripeptide sequence in the disintegrin domain, and specific interaction between recombinant human ADAM-15 and integrin αvβ3 is suggested to depend on the RGD sequence. ADAM-15 has been suggested of its interaction with integrins (αvβ3, α5β1, αIIβ3, α9β1) and possible involvement in cell-to-cell adhesion. Moreover, ADAM-15 in which R481, C487, D488, L489, P490, E491 and/or F492 among the amino acids 481-492 (RPTRGDCDLPEF) (loop sequence) including the RGD sequence of the disintegrin domain has been substituted with alanine, has decreased interaction ability with α9β1 integrin. Thus, R481, C487, D488, L489, P490, E491 and/or F492 of ADAM-15 are/is shown to be necessary for the interaction between ADAM-15 and α9β1 integrin (see Non-Patent Publication 6).
Since administration of recombinant ADAM-15 disintegrin domain inhibits proliferation of breast cancer cells, interaction between ADAM-15 and integrin appears to concern proliferation of cancer cells (see Non-Patent Publication 7).
ADAM-15 is also considered to be relevant to cell migration. For example, migration is reported to be reduced in NIH3T3 cell overexpressing ADAM-15 (see Non-Patent Publication 8). Additionally, overexpression of ADAM-15 in Jurkat cell is reported to enhance cell aggregation (see Non-Patent Publication 9). Moreover, ADAM-15 is reported to co-localize with a cell adhesion molecule VE cadherin (see Non-Patent Publication 10). Accordingly, ADAM-15 is considered to have an important role in cell-to-cell adhesion.
ADAM-15 is expressed in any body tissues as well as in vascular endothelial cells, and angiogenesis is reported to be suppressed in ADAM-15-knockout mice (see Non-Patent Publication 11). Furthermore, since stimulation of HUVEC with VEGF enhances expression of VEGFR-2 and ADAM-15, association between ADAM-15 and angiogenesis has been suggested (see Non-Patent Publication 12).
Since cell proliferation, cell migration, cell-to-cell adhesion and angiogenesis that have been reported of their connection with ADAM-15 are closely related to cancer and metastasis of cancer, ADAM-15 seems to be responsible for cancer and metastasis of cancer.
Since ADAM-15 expression is enhanced in rheumatoid arthritis, arteriosclerosis or the like, it also seems to be responsible for the process of tissue repair. Since ADAM-15 expression is also enhanced in the infarction site and the non-infarction site during the early phase of myocardial infarction, it seems to be responsible for the process of tissue repair in the heart.
However, no detailed report has been given on the association between the structure of ADAM-15 and these diverse functions of ADAM-15, and as to which component is exerting the functions of ADAM-15 has been unknown.
Monoclonal antibodies for ADAM-15, for example, 23G9 sold by R & D or the like are known but the relationship between these antibodies and the functions of ADAM-15 has not been reported. Moreover, there has been no report of an antibody that recognizes the ADAM-15 disintegrin domain.
Currently, although many drugs are known as therapeutic drugs for cancer, most of them have strong side-effects and thus development of a prophylactic drug and/or a therapeutic drug for cancer that is therapeutically effective with less side-effect has been anticipated. Previous antitumor agents have been developed to be drugs with less side-effect that can treat cancer by exerting specific cytocidal effect or cytostatic effect against cancer cells. In fact, however, most of these drugs also act on normal cells, causing severe side-effects.    [Patent Reference 1] U.S. Pat. No. 5,830,742    [Patent Publication 2] U.S. Pat. No. 6,013,466    [Non-Patent Publication 1] Almeida, E. A. et al., Cell, 81, 1095-1104, 1995    [Non-Patent Publication 2] Wen, C. et al., Development, 124, 4759-4767, 1997    [Non-Patent Publication 3] Tortorella, M. D. et al., Science, 284, 1664-1666, 1999    [Non-Patent Publication 4] Alfandari, D. et al., Dev. Biol., 182, 314-330, 1997    [Non-Patent Publication 5] Zhang, X. P. et al., J. Biol. Chem. 273, 7345-7350, 1998;    [Non-Patent Publication 6] Nath, D. et al., J. Cell Sci. 112, 579-587, 1999 P. 468-473.    [Non-Patent Publication 7] Eto, K. et al. J. Biol. Chem. 277, 17804-17810, 2002    [Non-Patent Publication 8] Trochon-Joseph, V., et al., Cancer Res, 64, 2062-2069, 2004    [Non-Patent Publication 9] Herren, B., et al., Exp Cell Res, 271, 152-160, 2001    [Non-Patent Publication 10] Charrier, L., et al., J Biol Chem, 282, 16948-16958, 2007    [Non-Patent Publication 11] Ham, C., et al., Exp Cell Res, 279, 239-247, 2002    [Non-Patent Publication 12] Horiuchi, K., et al., Mol Cell Biol, 23, 5614-5624, 2003    [Non-Patent Publication 13] Komiya, K., et al., Arthritis Res Ther, 7, R1158-1173, 2005